JP2955616B2 - Optical fiber for solar condensing - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical fiber for concentrating sunlight.

[0002]

2. Description of the Related Art As a conventional technique for concentrating sunlight, Asahi Glass Research Report 41 [2] (1991) P305-32.
As shown in FIG. 4, a method of condensing light using a condensing lens and guiding it to an optical fiber, and as shown in the Electrotechnical Laboratory, Vol. 50, No. 8, pages 9 to 18, There is a method using a transparent plate containing a phosphor.

[0003]

However, in these methods, for example, in the former method using a condenser lens,
It was necessary to change the direction of the condenser lens with the movement of the sun, which required a large-scale driving device. In the latter method using a transparent plate, it is necessary to take measures such as mounting a solar cell on a side surface of the transparent plate to extract the energy.

[0004]

In order to solve the above-mentioned problems, a phosphor is added to at least one of a core, a clad and a protective coating of an optical fiber, and a light having a high energy of 400 to 700 nm in the wavelength spectrum of sunlight is added. Light is transmitted to a wavelength having a small transmission loss of an optical fiber (for example, a wavelength of 850 to 160).
0 nm) and invented an optical fiber for transmission. According to the present invention, the cladding layer is composed of a plurality of layers, the refractive index of each cladding layer and the core is gradually increased from the outside to the inside, and each of the core and the cladding layer is exposed to sunlight incident from the outside. Condensed light that contains a phosphor that gradually converts light of a wide range of wavelengths to longer wavelengths in the cladding layer, and transmits sunlight energy as a wavelength with low transmission loss in optical fibers An optical fiber is provided.

In the present invention, the core and each clad layer contain a phosphor. Cyanine compounds (for example, D
CM (4-dicyanomethylene-2-methyl-6-p-dimethylaminostyryl-4H-pyran (4-dicyanomethyl
ene-2-methyl-6-p-dimethylaminostyryl-4H-pyran)),
DOTCI (3,3'-diethyl-2,2'-oxatricarbocyanine iodide (3,3'-diethyl-2,2'-oxatric
arbocyanineiodide))), oxazine-based compounds (eg, Cresyl violet, Oxazine 1, perylene-based compounds (eg, luminogen)
The organic phosphor of (Lumogen) F (BASF) can convert light having a wavelength of 400 to 700 nm of sunlight into about 600 to 800 nm. Nd ³⁺ ion or Yb ³⁺ ion of the inorganic phosphor converts light having a wavelength of about 800 nm into 1000 nm,
^{The 3+} ions convert light having a wavelength of about 800 nm to 1550 nm. By adding this organic phosphor or inorganic phosphor,
Sunlight can be converted into light having a wavelength with low transmission loss of the optical fiber. The inorganic phosphor is preferably an inorganic compound containing Er ³⁺ ion, Nd ³⁺ ion or Yb ³⁺ ion. The inorganic compound may be a salt (eg, a halide such as chloride, bromide and iodide). An example of a salt is E
rCl _3, NdCl _3, YbCl _3, and the like. When the core is made of an inorganic substance such as SiO ₂ , the core may contain an inorganic phosphor and the cladding layer may contain an organic phosphor. When the core is plastic, it is possible to use an organic phosphor having similar characteristics instead of the inorganic phosphor, and both the core and the cladding layer contain the organic phosphor.

[0006] The core is made of an inorganic substance such as SiO ₂ or an organic substance such as polymethyl methacrylate, polycarbonate, or polystyrene. The core diameter is usually 50 to
200 μm. The phosphor contained in the core is, for example, an inorganic phosphor such as Nd ³⁺ ion. The content of the phosphor is usually 0.5 to 10% by weight, preferably 2 to 10% by weight.
5% by weight. Since the core contains the phosphor, light having a wavelength of 700 to 800 nm is emitted from 1040 to 1100.
It is converted to light with a longer wavelength of nm.

The cladding is made of polymethyl methacrylate,
Made of organic materials such as polycarbonate and polystyrene. The thickness of the cladding is usually 30 to 100 μm. The phosphor contained in the clad is, for example, an organic phosphor such as cyanine-based DODCI. The content of the phosphor is usually 5 to 1000 μmol / l, preferably 10 to 100 μmol / l. When the clad contains the phosphor, light having a wavelength of 600 to 700 nm is converted into light having a longer wavelength of 700 to 800 nm.

When there are a plurality of clad layers, the kind and the amount of the phosphor contained in each clad are changed according to the number of clad layers. For example, if there are three cladding layers, the outermost layer contains DCM (converting 400-500 nm to 600-700 nm) and the intermediate layer is Cresy
l violet (conversion from 500 to 600 nm to 600 to 700 nm), and the innermost layer is DOTCI (600 to 700 nm).
nm to 700-800 nm).

[0009] The optical fiber for concentrating sunlight of the present invention may have a protective coating layer. The protective coating layer is transparent to the solar spectrum. The protective coating layer is made of nylon, acrylic, or the like. The protective coating layer may contain a phosphor. The kind and amount of the phosphor contained in the phosphor are the same as those of the cladding layer. The length of the solar condensing optical fiber is 5-1 in consideration of efficiency.
It is up to about 0 km. The solar concentrating optical fiber may be in a straight form or it may be wound with a sufficiently large bend radius without damaging the optical fiber. The minimum bending radius is usually at least 5 cm. The cladding layer or the protective coating layer of the optical fiber may be cylindrical,
Or you may have a plate-shaped part.

The present invention will be described in more detail with reference to the accompanying drawings. FIG. 1 is a schematic longitudinal sectional view of a solar light collecting optical fiber as a reference example having one cladding layer and a protective coating layer. The optical fiber 10 for concentrating sunlight has a core 11, a cladding layer 12, and a coating layer 13. For example, light of 400 to 700 nm having high energy in the wavelength spectrum of sunlight with an organic phosphor is converted to 700 to 1000 nm.
Is converted into light having a wavelength of 700 to 1000 nm, which is capable of converting light having a wavelength of 700 to 1000 nm into light having a wavelength of 1000 to 1600 nm, which has a small optical fiber transmission loss. It is added to the core 11. Due to the cladding layer 12, sunlight 17 is converted to primary fluorescent light 18.
The primary fluorescent light 18 is converted into the secondary fluorescent light 19 by the core.
(Propagating light 191 and emission light 192). The two-stage wavelength conversion effectively converts sunlight into light with a wavelength that minimizes the transmission loss of the optical fiber. Of the light emitted in all directions, the light emitted in the direction of total reflection is used as the core. It can be confined inside and transmitted directly to a distant place where energy is required by light.

It is also possible to add n different cladding layers to each of the cladding layers and convert the cladding layers into light having a wavelength with a small transmission loss in the optical fiber by combining them. For example, FIG. 2 shows three cladding layers (A
1 is a schematic longitudinal sectional view of an optical fiber for condensing sunlight of the present invention having a layer, a B layer and a C layer). 400 nm wavelength 6
When there is an A layer 24 for converting to 00 nm, a B layer 23 for converting 500 nm to 600 nm, a C layer 22 for converting 600 nm to 800 nm, and a core 21 for converting 800 nm to 1000 nm, the light having a wavelength of 400 nm of sunlight Is converted by the A and C layers, and light having a wavelength of 500 nm is converted by the B and C layers.
After the light of the wavelength of 00 nm is converted by the C layer, it is 1000
Converted to nm.

In order to perform total reflection, the refractive index of the inner layer needs to be higher than that of the outer layer. An optical fiber similar to the optical fiber of the present invention is, for example, an optical fiber disclosed in JP-A-63-56610. However, this is intended to convert ultraviolet light into visible light and apply it to an ultraviolet sensor or the like.
It does not aim to convert the wavelength of light step by step to obtain light of a wavelength with a small optical fiber transmission loss.

FIG. 3 is a perspective view showing one embodiment of the optical fiber for concentrating sunlight of the present invention. A solar condensing optical fiber 32 having a fiber end 31 and being wound;
Also, a transmission optical fiber 33 connected to the sunlight condensing optical fiber 32 is shown. The sunlight condensing optical fiber 32 is wound so as to receive sunlight efficiently. The solar condensing optical fiber can be wound evenly with a curvature greater than the one that does not damage the optical fiber in order to accumulate light of sufficient energy, thereby obtaining a large length in a small required space be able to. Also,
A mirror is attached to the end 31 of the sunlight collecting optical fiber to collect light in the direction in which the light is to be transmitted, and the transmission optical fiber 33 is the same as the sunlight collecting optical fiber 32 except that it does not contain a phosphor. Can be used. FIG. 4 is a perspective view showing another embodiment of the optical fiber for condensing sunlight of the present invention.
An optical fiber 42 for concentrating sunlight and an optical fiber 43 for transmission having a fiber end 41 are shown. The cladding layer or the protective coating layer of the optical fiber 42 for concentrating sunlight has a plate shape, not a cylindrical shape. Thereby, the light-collecting area can be increased, and the light-collecting efficiency can be further increased.

[0014]

Preferred embodiments of the present invention will be described below with reference to examples. Example 1 The core (0.4 mm in diameter) is made of glass mainly composed of SiO ₂ ,
For the cladding layer (one layer, thickness: 0.1 mm), an optical fiber made of transparent acrylic was used. The core was doped with Nd ³⁺ ions (3.3% by weight) as an inorganic phosphor. The dope is formed by a liquid immersion method in which NdCl ₃ is dissolved in a solvent (for example, water or alcohol) and the soot is impregnated.
It was carried out by a gas phase method in which dCl ₃ was vaporized and contained.
On the other hand, a cyanine dye (DODCI) or an oxazine dye was added to the cladding layer. The cladding layer is DODC
I was contained at 100 μmol / l.

[0015]

According to the present invention, light obtained by wavelength conversion of sunlight can be directly propagated into an optical fiber, so that light energy can be efficiently transmitted to a distant place.

[Brief description of the drawings]

FIG. 1 is a schematic longitudinal sectional view of an optical fiber for concentrating sunlight of the present invention having one clad layer.

FIG. 2 is a schematic longitudinal sectional view of a solar light collecting optical fiber having three cladding layers.

FIG. 3 is a perspective view showing one embodiment of an optical fiber for concentrating sunlight according to the present invention.

FIG. 4 is a perspective view showing another embodiment of the optical fiber for concentrating sunlight of the present invention.

[Explanation of symbols]

 10, 32, 42: optical fiber for concentrating sunlight, 11, 21, core: 12, 22, 23, 24: cladding layer, 13: coating layer, 31, 41: fiber end, 33, 43: light for transmission fiber.

──────────────────────────────────────────────────の Continuation of the front page (51) Int.Cl. ⁶ Identification symbol FI G02B 6/00 386 G02B 6/00 386 6/22 6/22 (56) References JP-A-2-46409 (JP, A) JP-A-63-318503 (JP, A) JP-A-3-251727 (JP, A) JP-A-49-16443 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) G02B 6/00 301 G02B 6/16-6/22

Claims (4)

(57) [Claims] 1. A cladding layer comprising a plurality of layers, wherein the refractive indices of the cladding layers and the core are increased stepwise from the outside to the inside, and each of the core and the cladding layer is provided with a solar light incident from the outside. A solar cell that contains a phosphor that gradually converts light with a wide wavelength range to longer wavelengths in the cladding layer, and that transmits solar energy as a wavelength with low optical fiber transmission loss. Optical fiber for light. 2. The phosphor according to claim 1, wherein the phosphor is an inorganic phosphor or an organic phosphor, and the inorganic phosphor is Er ³⁺ ion, Nd ³⁺ ion or Y
2. The optical fiber for concentrating sunlight according to claim 1, wherein the optical fiber is b ³⁺ ion, and the organic phosphor is an oxazine-based compound, a cyanine-based compound, or a perylene-based compound. 3. The optical fiber for concentrating sunlight according to claim 1, wherein the optical fiber is straight or wound with a bending radius large enough not to damage the optical fiber. 4. The optical fiber for condensing sunlight according to claim 1, wherein the cladding layer or the protective coating layer of the optical fiber is cylindrical or has a plate-like portion.